* src/gram.h (item_number_t): New, the type of item numbers in

* src/gram.h (item_number_t): New, the type of item numbers in
RITEM.  Note that it must be able to code symbol numbers as
positive number, and the negation of rule numbers as negative
numbers.
Adjust all dependencies (pretty many).
* src/reduce.c (rule): Remove this `short *' pointer: use
item_number_t.
* src/system.h (MINSHORT, MAXSHORT): Remove.
Include `limits.h'.
Adjust dependencies to using SHRT_MAX and SHRT_MIN.
(shortcpy): Remove.
(MAXTABLE): Move to...
* src/output.c (MAXTABLE): here.
(prepare_rules): Use output_int_table to output rhs.
* data/bison.simple, data/bison.c++: Adjust.
* tests/torture.at (Big triangle): Move the limit from 254 to
500.
* tests/regression.at (Web2c Actions): Ajust.
Trying with bigger grammars shows various phenomena: at 3000 (28Mb
of grammar file) bison is killed by my system, at 2000 (12Mb) bison
passes, but produces negative #line number, once fixed, GCC is
killed while compiling 14Mb, at 1500 (6.7 Mb of grammar, 8.2Mb of
C), it passes.
* src/state.h (state_h): Code input lines on ints, not shorts.